There’s a specific feeling that happens when a training block shifts from base to build. You stop thinking in months and start counting weeks. You open the weather app and check the race location instead of your own city. You pull up Google Maps Street View, click through the course, and try to read the surface from satellite imagery.
Then the gear decisions start to feel real. Tire choice, tire pressure, nutrition plan, kit selection — all of it suddenly matters in a way it didn’t a few weeks ago. You make a plan, then remake it. On top of that your legs are growing heavy, and that fatigue becomes the new normal until race day.
That’s where I’ve been lately in my Unbound 200 build phase. I felt the same shift before my first Ironman, and again before Kona: the training gets more race-specific, and everything in your head does too.
What Is the Build Phase, and How Long Should It Be for Unbound 200?
The build phase is where training starts to look like racing. Workouts become more specific—longer, or higher intensity, or more race-like in structure, depending on what the event demands. For a 200-mile gravel race, that mostly means increasingly long efforts at endurance pace, with some targeted intensity layered in to prepare for what the course has in store.
The build phase is typically short and capped in a periodized plan. Training stress ramps up fast with the intensity, and fatigue stacks quicker than in base. That’s why you need a taper to shed it and actually peak. I designed mine for 8 weeks—two 4-week mesocycles, recovery week at the end of each.
What I’m Training For: The Demands of Unbound 200
A few things shape everything about my Unbound 200 build phase:
The elevation profile. The typical rolling hills of the Unbound course are often described as “death by a thousand cuts.” There’s no single long climb high into a mountain. But the terrain is constantly undulating and the downhills don’t give you much momentum back over loose gravel. The ability to regulate power output on the uphills is needed to keep pedaling for a full day in the saddle.
The technical demands. Flint Hills gravel is sharp and loose meaning sudden line changes can cut tires. The mud, when it’s wet, is famously peanut-butter-thick. It can grab your tire and throw you off line, meaning bike handling skills need to be sharp.
The sheer length of the day. For most age groupers, myself included, finishing Unbound is a 12 to 16 hour-effort. The muscular and skeletal demands of sitting in one position for that duration — back, hips, core, hip flexors — are different from Ironman, where you at least get to change positions between disciplines.
Four Training Adaptations I’m Targeting
- Comfort on the bike for 12-16 hours
- Stamina to handle repeated effort surges over 200 miles
- Leg strength for low-cadence power up hills
- Gut training to handle the high carbohydrate intake
How I’m Targeting Each Adaptation
Bike Comfort and Long Ride Endurance
The foundation of my Unbound 200 build phase is the long ride progression. Weekends are structured around increasingly long efforts on the gravel bike building towards a 10-12 hour peak day. More on the specific progression below. The goal is not just fitness; it’s teaching my body to maintain position, stay efficient, and continue moving.
Stamina: Zone 3 Intervals and What Polarized Training Looks Like Here
For gravel racing, where you’re not targeting a single sustained power output but rather managing a long continuous effort with variable terrain, zone 3 intervals build the stamina to keep pushing when you’re already tired. I tack these onto the end of long endurance rides to simulate that late-race feeling of continuing at effort when the legs are already loaded. Most of my training is still done at a lower intensity roughly following the 80/20 principle.
Muscular Strength and Hill Capacity: Hill Reps and MTB Rides
I live in Chicago, so hills require creativity. Most hill reps happen on the trainer at 50–60 rpm to mimic real-grade torque. I also do MTB rides with my 30lb toddler riding shotgun. The extra weight of the heavy bike and toddler builds the leg strength for Unbound’s endless rollers.
Nutrition: Practicing and Tweaking on Every Long Ride
This is where I spend more mental energy than anywhere else. My goal is 80-100g of carbs per hour and sufficient electrolyte replenishment. I’ll need to figure out how my gut handles the combination of race-duration effort and high-carb fueling. Every long ride is a test of liquid volume, sodium concentration, real food vs. gels. Taking in all that food and drink can be tricky on technical terrain and takes some practice.
Build Phase Workout Progressions for Unbound 200
Hill Rep Progression
Starting point: 10 x 30 seconds, low cadence (50–60 rpm)
Ending point: 4 x 4 minutes, low cadence
The progression toward 4-minute efforts mirrors what you’d actually experience on Unbound’s rolling hills — not short punchy climbs, but sustained moderate grades.
Zone 3 Interval Progression
Starting point: 4 x 16 minutes at zone 3
Ending point: 5 x 20 minutes at zone 3
The 16-minute starting point was a natural step up from the zone 4 work I was doing in base phase — a bit more total volume at a slightly lower intensity ceiling. I attach these to the end of my long rides rather than doing them fresh.
Long Ride Progression
Starting point: 4.5 hours
High point: 10-12 hours (with most long rides in the 6.5–8 hour range)
My longest rides at the end of base were about 3.5 hours. When you’re training for shorter endurance races, you may want your longest rides to progressively increase in duration during the base phase and then switch to higher intensity but shorter sessions in the build phase. That works well for races where your expected race effort is in the zone 3 to zone 4 range. With a race this long, my race effort is going to be in zone 2. So to follow the principle of workouts becoming increasingly race-like in the build phase, I have those longest rides in my build phase.
If you can’t consistently fit very long rides into your schedule, you can break it up. Two back-to-back long rides at the end of the week still trains the body to adapt to accumulated fatigue. I think you should aim to do at least one long effort in the 120-150 mile range (or ~70% race time equivalent) before race day. This is long enough to test your setup, your nutrition, and your mental game under real conditions. But if you can only consistently manage 4–5 hour rides week after week, you can still pull together a good training build. Consistent weekly volume compounds and missing a few long efforts is ok.
Finding time for a 8-10 hour ride is the hardest part of this whole plan. Getting out for that long week after week requires coordination with my partner, flexibility from both of us, and accepting that some weeks it’s just not going to happen.
Free download: Suggested Build Phase Workouts for Unbound 200
A printable/saveable reference sheet with the full hill rep, zone 3 interval, and long ride progressions — plus the strength maintenance exercises listed below. [Download the workout guide → HERE]
What a Typical Training Week Looks Like
I aim for six rides per week, roughly structured like this:
- Monday: day off or recovery spin and weights
- Tuesday: Zone 2 endurance ride with some short, maintenance VO2Max intervals
- Wednesday: High intensity — hill reps or VO2 work
- Thursday: Zone 2 endurance
- Friday: Easy recovery ride, 1-1.5 hours
- Saturday: Long ride with ending with zone 3 intervals
- Sunday: muscular strength ride, 1–1.5 hours with the loaded-up MTB
Weekday sessions are designed to fit into a window of 1–1.75 hours, which I can usually wake up early enough to squeeze in before work. Some weeks, Friday becomes another rest day. Some weeks the long ride scheduled for 8 hours ends after 5 hours because life happened. The goal is hitting most of the plan, most of the time, not executing every session perfectly.
Other Build Phase Priorities
Each of these could be its own post — and will be, eventually.
Nutrition plan. I learned from Ironman racing just how complicated it can be to find the right mix of carbs, fluid, and electrolytes to fuel a 12+ hour race without your stomach revolting. I’m still working on dialing my options and mixing in some real food in addition to gels and drink mix.
Bike fit. Still in progress. I’ve been working through recommendations from AI bike fitting tools and will publish a full post on that process when I have more to report. [Bike Fit post — coming soon]
Gear and navigation. Getting this sorted to test on the longest training rides is key. If it turns out a light or gps battery doesn’t last as long as it’s supposed to, you can fix it before race day. This eats up a lot of my mental energy so I like to get this nailed down early.
Strength Maintenance in the Build Phase
Given the increase in training stress during the build phase, I reduce the frequency of strength sessions and keep the weight low. I try to keep this as simple and flexible as possible so that I actually do it.
Lower body strength: I pick two exercises from the list below based on what I’m feeling that day. Low weight, 3 sets of 12–15 reps, done in 15 minutes.
- Lunge variations
- Squat variations
- Deadlifts
- Hip thrusts
- Step-ups
Core: Twice per week, 5 minutes each. Plank variations, crunches, mountain climbers, dead bugs, bird dogs, glute bridges. I pick a few exercises to do for a minute each. The goal is keeping the core strong enough to maintain position on a long ride.
FAQ: Unbound 200 Build Phase Training
How long should the build phase be for Unbound 200?
Typically 6-8 weeks (two mesocycles in my self-coached plan). Each mesocycle is three to four weeks of progressively building training stress followed by a recovery week. Beyond the two mesocycles, the accumulated stress should be shed with a taper before race day.
What workouts should be included in the build phase?
For a long gravel race specifically: increasingly long weekend rides, low-cadence hill reps (on a trainer if you also live where it’s flat), and zone 3 intervals under fatigue.
How many long rides should you do before Unbound 200?
In an ideal world, you would gently progress one weekend long ride each week (cutting that volume back significantly during your recovery weeks). Consistency matters more than hitting every planned long ride. I would aim for at least one long ride in the range of 120-150 miles of mostly gravel, or get close to 70% of your expected gravel race time (not mileage) on pavement. This is where you can do a full test of your setup and nutrition plan before race day.
How do you train for Unbound 200 as a triathlete?
The training and structure transfers well. If you’ve done Ironman training, you have a good foundation. The key differences: all or most of your work shifts to the bike. Focus on long ride volume, low-cadence strength work, and nutrition practice. Keeping up with some swimming and running can work well for continuing to build aerobic endurance. The pacing instincts from Ironman (don’t go out too hard, regulate power on climbs) apply directly.
What’s Next
I’m currently in the middle of my build for Unbound 200. The training stress is picking up and fatigue accumulating. But, my fitness feels good. I’ll spend the next few weeks sorting out the race prep to make sure I can nail nutrition and handle (or prevent) any mechanical issues on race day.
Next post: how I’m structuring the peak phase and taper — and what the final weeks before Unbound actually look like.
